Manhole cover

ABSTRACT

The invention concerns a manhole cover with a frame (1) and a grating (3) or cover fitting flush with the frame (1). In order to secure the cover (3) in such a way that it can be easily removed and put back in place, a one-piece securing element (4a) is attached to the frame (1), the securing element (4a) having a locking element (7) at the end of a tab-like retaining element (6) extending obliquely upwards. The locking element (7) engages against a locking surface (9) at the bottom of a recess (8) in the surface of the grating (3) or cover. To unlock the manhole cover, the locking element (7) can be pulled away from the locking surface (9) with a special tool, e.g. a pair of pliers, the retaining element (6) being bent elastically. The securing element (4a) is mounted on the frame (1), embracing shoulders (5a, 5b) so that it is secured by a snap-in connection. The securing element can also be attached to the cover or grating and engage against a locking surface on the frame.

The invention relates to a manhole cover which comprises a frameanchored in the ground and having a lower-lying supporting shoulder atleast partially surrounding the frame aperture, and a grating or coverresting on said shoulder and fitting flush with the frame aperture.

Manhole covers of this kind must be secured in such a way that thegrating or cover cannot jump out of the frame due to the action ofvehicles driving over the top and, as far as possible, also in such away that they cannot be removed by unauthorised persons. In a knownsolution, grating and frame are screwed together.

It is the object of the invention to indicate a manhole cover of thegeneric type with a securing device which allows the grating or cover tobe fitted and removed as easily as possible.

The invention, as characterised in the claims, creates a manhole coverin which the grating or cover is secured automatically when fitted,without the necessity for an additional operation. Removal is equallysimple, it being easy to design the manhole cover in such a way that thegrating or cover can be removed only by means of a special tool, buteasily and rapidly with it.

Further advantages of the invention consist, in particular, in the factthat the frame can be simpler in design than if a screwed connectionwere provided, and in the simplification of the production of the frameand of the grating or cover, since the drilling of holes and tapping ofthreads is superfluous and operations are thus omitted.

The invention is explained in greater detail below with reference toFigures which represent only embodiments:

FIG. 1a shows a plan view of a first manhole cover according to theinvention,

FIG. 1b shows a sectioned perspective representation of the manholecover according to FIG. 1a,

FIGS. 2a-c show the opening of the manhole cover according to FIGS. 1a,1b, in section,

FIG. 3 shows a second manhole cover according to the invention, inperspective,

FIG. 4 shows a further manhole cover according to the invention, insection,

FIGS. 5a-f show securing elements and their anchoring on the frame inthe case of various manhole covers according to the invention, insection,

FIGS. 6a,b show a further manhole cover according to the invention,

FIG. 7 shows a variant of the manhole cover according to FIGS. 6a,b, insection,

FIG. 8 shows a further manhole cover according to the invention, insection,

FIG. 9 shows a manhole cover according to the invention with a securingelement attached to the grating, in section, and

FIG. 10 shows a variant of the manhole cover according to FIG. 9,likewise in section.

The manhole cover depicted in FIGS. 1a, 1b has a frame 1 with atwo-part, lower-lying supporting shoulder 2, on which a grating 3 rests.

According to the invention, two securing elements 4a,b arrangeddiametrically opposite to one another are attached to the frame. Theyare preferably of one-piece spring-steel construction and mounted on theframe 1. The securing element 4a here fits over the top of shoulders5a,b on both sides, thus producing a snap-in connection which secures iton the frame 1. The securing element 4a comprises a retaining element 6,which is designed as a resilient tab extending obliquely upwards andadjoining which is a locking element 7. On its upper surface, thegrating 3 has a recess 8, the base of which is formed by a lockingsurface 9. The locking element 7 and the locking surface 9 are inengagement with one another and in this way secure the grating 3. Thesecond securing element 4b is preferably of identical design to thefirst locking element 4a but can also be replaced by some other device,e.g. by a projection on the frame which engages in a recess on thesurface of the grating (for further possibilities see below).

Suitable materials for securing elements are, in particular, metallicmaterials, in particular spring steel and other steel grades or castiron containing spheroidal graphite, as well as corrosion-resistantplastics.

As depicted in FIGS. 2a-c, the manhole cover is unlocked by pulling backthe locking element 7 from the locking surface 9, the retention part 6being elastically deformed. The grating 3 can then simply be lifted off.To prevent theft, it is advantageous to design the securing element 4aand, in particular, to dimension the retaining element 6 in such a waythat a deformation sufficient for the unlocking of the grating 3 is onlypossible using a special tool, e.g. a pair of pliers applied to the endof the locking element 7 and supported against the frame 1.

The mounting of the grating is facilitated by the fact that it ischamfered somewhat at the bottom. As soon as it has reached the closureposition, the lock snaps in automatically.

FIG. 3 shows a manhole cover according to the invention in which a cover3' can be fitted positively into the frame 1--projections 10 on theframe 1 engaging in recesses 11 on the cover 3'--in such a way that asingle securing element 4 is sufficient. The latter is here flanked byprojections 10 and thereby especially protected.

FIG. 4 shows a manhole cover according to the invention likewise havingonly one securing element 4, which is of identical design to the manholecovers already described. Diametrically opposite the securing element 4,the edge of the cover 3' is chamfered and projects under acorrespondingly chamfered overhanging edge part of the frame 1, with theresult that the cover 3' is also locked there.

FIGS. 5a-f show various possibilities for the design of the securingelements 4 and their anchoring on the frame 1. In the embodimentaccording to FIG. 5a, the securing element 4 is particularly easy tomount and remove since the shoulders of the embodiments described aboveare absent. The securing element 4 is nevertheless adequately secured bythe projecting edge 12, over which the securing element 4 engages.

In the case of the securing elements according to FIGS. 5b-e, release ismade easier in comparison with the embodiments described above, becauseof the greater length of the retaining element 6 in combination with thesame cross-section of the latter. The embodiments according to FIGS.5d,e have the advantage that the securing element 4 can in each case bemounted on the frame 1 from above, i.e. it can readily be mountedsubsequently and exchanged more easily.

In the case of the securing element according to FIG. 5f, engagementover angular shoulders or projections is avoided, facilitating itsfitting and removal. Since the securing element 4 cannot be removedwithout considerable elastic deformation, it is nevertheless reliablysecured on the frame 1.

FIGS. 6a,b show a manhole cover according to the invention which canalso be of sealing design. The securing element 4 is embedded in theframe 1. As indicated by an arrow, the locking element 7 presses with aresidual stress against the locking surface 9, which is inclined towardsthe edge of the recess 8 for the purpose of easier unlocking. The cover3' is thus pressed against the frame 1.

FIG. 7 shows a variant of the embodiment according to FIGS. 6a,b with asecuring element 4 mounted with engagement over a shoulder 5.

FIG. 8 depicts a manhole cover according to the invention in which therecess 8 is formed on the side of the cover 3' and is limited towardsthe top. In this embodiment, access to the securing element 4 withoutspecial tools is made more difficult and particularly effectiveprotection against theft is provided.

FIG. 9 shows an embodiment in which the securing element 4 is embeddedin the grating 3 and its retaining element 6 is designed as a resilienttab extending obliquely downwards. The locking element 7 is inengagement with a locking surface 9 in a recess 8 on the underside ofthe frame 1.

Finally, FIG. 10 shows a variant of the embodiment according to FIG. 9in which the securing element 4 is mounted on the grating 3 and lockedby means of snapping in. In this embodiment, the securing element 4 canbe removed very easily after the removal of the grating 3.

We claim:
 1. A manhole cover which comprises:(a) a frame having alower-lying supporting shoulder at least partially surrounding theframe; (b) a cover dimensioned and configured to receive into the frame;and (c) a securing element dimensioned and configured to maintain thecover with the frame, the securing element including:(i) a resilientportion extending from the frame; and (ii) an engaging portion dependingfrom the resilient portion for releasibly engaging the cover to inhibitrelative movement of the cover from the frame.
 2. A manhole cover asrecited in claim 11, wherein said cover is configures as a gratingconfiguration.
 3. A manhole cover comprising:(a) a frame defining aframe aperture, said frame anchored in the ground and having alower-lying supporting shoulder at least partially surrounding the frameaperture; (b) a grating resting on said supporting shoulder and fittingflush with said frame aperture, said grating defining a locking surface;(c) at least one securing element being attached to said frame by asnap-in arrangement for securing said grating to said frame, said atleast one securing element comprising:(i) a resilient retaining elementdefining a locking element extending therefrom, said locking elementbeing dimensioned and configured so as to detachably engage with saidlocking surface of said grating such that said locking elementdisengages with said locking surface upon elastic deformation of saidresilient retaining element.
 4. A manhole cover as recited in claim 3,wherein said locking surface forms the base of a recess on said gratingin which said locking element engages.
 5. A manhole cover as recited inclaim 4, wherein said recess is formed on an upper surface of saidgrating and said retaining element is designed as a resilient tabextending obliquely upwards or downwards.
 6. A manhole covercomprising:(a) a frame defining a frame aperture, said frame anchored inthe ground and having a lower-lying supporting shoulder at leastpartially surrounding the frame aperture; (b) a cover resting on saidsupporting shoulder and fitting flush with said frame aperture, saidcover defining a locking surface; (c) at least one securing elementbeing attached to said frame by a snap-in arrangement for securing saidcover to said frame, said at least one securing element comprising:(i) aresilient retaining element defining a locking element extendingtherefrom, said locking element being dimensioned and configured so asto detachably engage with said locking surface of said cover such thatsaid locking element disengages with said locking surface upon elasticdeformation of said resilient retaining element.
 7. A manhole cover asrecited in claim 6, wherein said locking surface forms the base of arecess on said cover in which said locking element engages.
 8. A manholecover comprising:a frame anchored in the ground and having a lower-lyingsupporting shoulder at least partially surrounding the frame aperture, agrating or cover fitting flush with the frame aperture, said grating orcover defining a locking surface, at lest one securing element attachedto the frame by a snap-in arrangement for detachably securing the coverin the frame, said securing element comprising: a resilient retainingelement and a locking element extending from the retaining element andengaging the locking surface on the grating or cover, from which it canbe pulled back by elastic deformation of the retaining element.
 9. Amanhole cover according to claim 8, wherein the locking surface formsthe base of a recess on the grating or cover in which the lockingelement engages.
 10. A manhole cover according to claim 9, wherein therecess is formed on the upper surface of the grating or cover and theretaining element is designed as a resilient tab extending obliquelyupwards.
 11. A manhole cover according to claim 9, wherein the recess isformed on the side of the grating or cover and is limited towards thetop.
 12. A manhole cover according to claim 9, wherein the lockingsurface is inclined towards the edge of the recess.
 13. A manhole coveraccording to claim 8, with the retaining element pressing the lockingelement with a residual stress against the locking surface.
 14. Amanhole cover according to claim 8, wherein the retaining element ismanufactured in one piece from a metallic material.
 15. A manhole coveraccording to claim 14, wherein the metallic material is steel orspheroidal graphite.
 16. A manhole cover according to claim 8, whereinthe retaining element manufactured in one piece from plastic.
 17. Amanhole cover comprising:a frame anchored in the ground and having alower-lying supporting shoulder at least partially surrounding the frameaperture, said frame defining a locking surface, a grating or coverfitting flush with the frame aperture, at least one securing elementattached to the grating or cover by a snap-in arrangement for detachablysecuring the cover in the frame, said securing element comprising: aresilient retaining element and a locking element extending from theretaining element and engaging the locking surface on the frame, fromwhich it can be pulled back by elastic deformation of the retainingelement.
 18. A manhole cover according to claim 17, wherein the lockingsurface forms the base of a recess on the frame in which the lockingelement engages.
 19. A manhole cover according to claim 18, wherein therecess is formed on the underside of the frame and the retaining elementis designed as a resilient tab extending obliquely downwards.
 20. Amanhole cover according to claim 18, wherein the locking surfaceinclined towards the edge of the recess.
 21. A manhole cover accordingto claim 17, wherein the retaining element pressing the locking elementwith a residual stress against the locking surface.